The routine maintenance of valves usually includes the periodic removal and replacement of packing materials around the valve stem. The packing materials are disposed around the valve stem and are located in a chamber in the valve bonnet. The packing material will sometimes include a lantern ring which is disposed between upper and lower portions of the packing material. The lantern ring is a metal ring having a plurality of radial conduits. The radial conduits of the lantern ring are aligned with a lubrication port extending through the wall of the bonnet into the packing chamber.
In some circumstances, the lantern ring will become stuck making it difficult to remove. To remove a stuck lantern ring, the mechanic usually uses a drill to form a series of circumferentially spaced holes on the lantern ring which are then tapped and threaded with a series of bolts. The bolts are pulled manually to lift the lantern ring out of the packing chamber.
This method of removing a stuck lantern ring has numerous drawbacks. It is difficult at best to insert a drill into a packing chamber without damaging the highly polished surfaces of the packing chamber and/or valve stem. Damage to those surfaces may result in the failure of the packing to provide a complete seal around the valve stem.
Various types of tools have been devised in the past for disassembling a valve. Such tools are disclosed in the patent to Fennema, U.S. Pat. No. 2,641,052; Fisher, U.S. Pat. No. 2,649,825; Boler, U.S. Pat. No. 1,934,255; and Sutton et al., U.S. Pat. No. 4,079,494. None of these references, however, disclose a tool for removing a stuck lantern ring from the packing chamber of a valve bonnet.